Such gas sensors have a detector element, which is specific to the gas to be measured and sends a measured signal that depends on the concentration of the measured gas. In particular, electrochemical gas sensors have been provided with a detector element designed as a measuring electrode that is specific to the gas to be measured. As they are described, for example, in DE 101 44 862 A1, semiconductor sensors with a usually heated ceramic semiconductor element consisting, for example, of SnO2 or an organic polymer semiconductor element, for example, Cu phthalocyanine, as well as catalytic heat tone sensors with a detector element, which is designed as a pellistor (detector bead) and is specific to the gas to be measured, are known. Because of their principle of action, catalytic heat tone sensors are used especially for measuring combustible and explosive gases, for example, methane.
Due to the steadily increasing requirements imposed on the maximum allowable gas concentrations at the workplace and because gases occurring in industry, for example, arsine, are also toxic even in the ppb (parts per billion) range and even at concentrations below 1 ppb, there is an increased need for compact, possibly portable gas sensors, in order to measure specific gas concentrations ranging from a few ppm to below 1 ppb, without having to resort to the very complicated measuring techniques that have hitherto been necessary, for example, mass spectrometry.